We are interested in how organisms perceive their own movements through somatosensation. Self- movement perception is thought to be important both for understanding the external world (i.e. as one passes his fingers over a bumpy surface) and for the on-line control of movement (i.e. as one tries to touch his own nose with his finger while his eyes are closed). To study this question, we use the rodent vibrissal system as a tractable mammalian model system because (1) the neuroanatomy for this system is relatively well-characterized, (2) the system is relatively easily accessible to experimental manipulation, and (3) the sensitivity of the system rivals that of human touch. Rodents use their vibrissae (whiskers) to sense the external world. By rhythmically sweeping their vibrissae back and forth in a behavior known as "whisking", the vibrissae contact objects near the face. This behavior allows the animal to form perceptions about its immediate surroundings. In forming these perceptions based on inputs from moving sensors, rodents must keep track of their own movements as well as external objects. The aims of this proposal are to determine: (1) how movement information that is "re- coded" at the periphery is processed in the thalamus (and subsequently relayed to the cortex of the brain), (2) the degree to which such information is combined with information about external objects, and (3) the neural mechanisms by which this processing occurs. A basic scientific understanding of how perception of self-movement is involved in motor control is currently lacking, and could potentially help us to understand a variety of neurological dysfunctions which result in motor control impairments, such as stroke and paralysis. Such an understanding could also inform the design of neural prosthetic devices aimed at restoring sensation and motor capabilities to patients with such impairments. Currently these prototype devices operate in the absence of somatosensory feedback are are consequently difficult for patients to control. The integration of intrinsic and extrinsic sensations may also be an important part of a broader sense of "self", which extends beyond the sensorimotor domain and is thought to be an important aspect of the human condition.